See the documentation.

1. Get Ganache-cli

   npm install -g ganache-cli
   

2. Run this:

   ganache-cli -d -i 437894314312
   

3. Clone Gnosis contracts, cd in there, and migrate the contracts onto the Ganache-cli instance with:

   cd path/to/gnosis-contracts
   npm install
   npm run migrate
   

4. Download gnosis.js and put it in an HTML file:

   <script src=gnosis.js></script>
   

5. Follow some tutorials:
   • API Overview
   • Events, Oracles, and Markets